# Similarity Similarity Similar Not Similar Similar triangles 1

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Similarity Similarity

Similar Not Similar

Similar triangles 1 Enlarge Scale factor k = 4. 5 cm 3 cm 4. 5 ---3 k = 1. 5 x = 1. 5 X 2. 2 cm = 3. 3 cm x cm

Similar triangles 2 Slide them Add new sizes Enlarge apart Scale factor k = 3 cm 2. 2 cm 4. 5 ---- 3 k = 1. 5 4. 5 cm x = 1. 5 X 2. 2 cm 1. 5 cm = 3. 3 cm x cm

Similar triangles 3 Slide them Add new sizes Enlarge apart Scale factor k = 3 cm 3. 3 ---2. 2 cm k = 1. 5 y cm y = 1. 5 X 3 cm x cm 3. 3 cm = 4. 5 cm x = 4. 5 - 3 cm x = 1. 5

Similar triangles 4 3. 3 cm Identify Reduce corresponding 3 sides Scale factor k = ---4. 5 cm 4. 5 k = 2/3 x = 2/3 X 3. 3 cm = 2. 2 cm x cm

Similar Area Maths homework tonight… Enlarge Scale factor k = 2 New area is 4 X the old New area is 22 X the old New area is K 2 X the old area

Similar Area Enlarge Scale factor k = 3 New area is 9 X the old New area is 32 X the old New area is K 2 X the old area

Similar Area Maths homework tonight… Reduction Scale factor k = ½ New area is ¼ X the old New area is ½ 2 X the old New area is K 2 X the old area

Similar Area 1 Enlarged Scale factor k = k=2 ? 28 cm 2 7 cm 2 6 cm 3 cm Area is 6 ---3 k 2 X original = 22 X as big = 4 X 7 cm 2 = 28 cm 2

Similar Area 2 Reduced Scale factor k = 2/3 81 cm 2 36 cm ? cm 22 9 cm 6 cm Area is 6 ---9 k 2 X original = (2/3)2 X as big = (4/9)X 81 cm 2 = 36 cm 2

Similar Volume Enlarge Scale factor k = 2 New volume is 8 X the old New volume is 23 X the old New Volume is K 3 X the old volume

Similar Volume 1 200 8 cm ? Enlarge Scale factor k =24/8 k=3 New volume = K 3 X the old = 33 X 200 ml = 27 X 200 ml = 5. 4 litres 24 cm

Similar Volume 2 £ 1. 62 6 cm £ 0. 48 ? 4 cm Reduce Scale factor k = 4/6 k = 2/3 3 the old price New. Volume price = =KK 3 X New X the old Volume = (2 /3) 3 X £ 1. 62 = 8/27 X £ 1. 62 = £ 0. 48

3 Formulae New Length = K 1 X old length New Area = New Volume = 2 K 3 K X old area X old volume